Comma lifecycle

[eccles]

I'm broadly up to speed in what happens during a comma's lifecycle but there are anomalies that I'm not too sure about.
Here's what I believe happens:
In the autumn, commas gradually alter their blood consistency so that they can withstand sub-zero temperatures. They eventually find a quiet spot, say under a blackberry leaf and hibernate through the winter. When days lengthen and temperatures reach sufficiently high levels they wake up, mate and produce eggs which hatch.
The offspring then split into two groups, one of which grows slowly to emerge as normal adults in late summer.
The other group feed up quickly to pupate and emerge in midsummer as the lighter hutchinsoni form. These immediately mate, lay eggs and produce young that continue feeding quickly to emerge as a second brood in late summer/early autumn. These again are the normal looking dark variant.
Both then overwinter as adults.

This summer, around mid-June I began to see lots of hutchinsoni. Then in mid-July I saw evidence of a second emergence but of dark form adults. Now, over the last few days I've been seeing what look like fresh hutchinsoni commas again.
So what will happen to the dark form commas? Will they produce another brood like the hutchinsoni form? Will we still get the slow form late summer emergence, or have they shot their bolt and emerged early?

Suggestions appreciated.

Thanks,
Mike.

[Pete Eeles]

Very interesting observation, Mike! I've not seen any fresh hutchinsoni for a while now. My comments below are all theory.

"So what will happen to the dark form commas?"
They will enter hibernation without reproducing.

"Will they produce another brood like the hutchinsoni form?"
Not this year.

"Will we still get the slow form late summer emergence, or have they shot their bolt and emerged early?"
I'm not sure what the "slow form late summer emergence" means. But I think that a) the dark form will continue to emerge and eventually hibernate and b) any "fresh" hutchinsoni will reproduce and, hopefully, their offspring will have enough time to get them through to hibernation.

Cheers,

- Pete

[eccles]

Thanks Pete. It's clearer now.
This is one that I took this afternoon, undoubtedly a hutchinsoni don't you think?

[Pete Eeles]

Looks like it to me - but the underside would be conclusive

Cheers,

- Pete

[Mikhail]

When I worked at Monks Wood in the 70s I became interested in the Comma, and specifically in what determined the production of hutchinsoni. In back numbers of various entomological magazines I found details of breeding experiments carried out by other people who had wrestled with this problem. I noticed a surprising fact: all Commas emerging up to the 10th July were reported to be hutchinsoni and those emerging later were of the dark form. Interestingly, the eponymous Mrs Hutchinson's brood yielded 100 per cent hutchinsoni, because they all emerged early. I concluded from this that almost certainly day length (photoperiod) was implicated , otherwise it would be difficult to explain such a switch over. It was gratifying, some years later, to learn that a Swedish entomologist had indeed confirmed that this was the case. It is not the case that some larvae develop slowly and others rapidly, but because eggs are laid in the spring over a prolonged period, some larvae inevitably are later to develop. In theory, there is no reason why you should not have a first brood entirely of hutchinsoni, and indeed I believe this may happen in some warm southern localities in warm years with an early spring.

Misha

[Padfield]

I was intrigued to note that in my local woods, the first commas of the year to emerge were all the 'normal' dark form. This was on 17th June:



The first hutchinsoni I saw was on 28th June:



Now they are both more or less equally common:



Guy

[Jack Harrison]

I raised a similar query about Small Tortoiseshells to which no one has replied. I repeat here:

I am confused as to the brood structure of Small Tortoiseshells. I saw new emergences on 15th June and they clearly were offspring of the hibernators. I had understood that these June individuals bred again to produce the late summer emergences (compare Comma life cycles). Yet I am still seeing huge numbers of pristine Tortoiseshells on 15th July (plus the occasional very tatty one). I cannot imagine that these are the offspring of the mid-June emergence so presumably late emerging offspring of the hibernators.

I can only surmise that the life cycle is complicated. Some develop quickly and emerge mid June. These breed and we see their offspring late August/September. Meanwhile, some (from hibernators) develop much more slowly and these are the ones we are seeing now in mid July in huge numbers that will eventually mingle with their “nieces and nephews” in late summer. But I really don’t know what happens. Any better ideas?

Jack

[Pete Eeles]

Hi Jack,

According to "Thomas and Lewington" - "Butterflies of Britain and Ireland", what you've suggested is exactly what happens. They say that 2 broods is typical "down south" and 1 brood typical "up north".

Cheers,

- Pete

[Jack Harrison]

Pete. Your comments didn’t quite clear up my question.

I appreciate that there are two broods in the south (and experience living in Scotland certainly points to just one brood in the Highland Glens), is it a full two broods here or a mix of double and single broodiness? My thoughts are that the June emergence is those fast developing individuals that then breed again (flying late August onwards prior to hibernation) whereas the July ones are merely the slower growing ones that also do not breed until next.

In other words, I suggest that the Small Tortoiseshell lifecycle exactly parallels that of the Comma but it is not, as is the case with Comma, possible to tell by appearance precisely what is occurring.

Jack